Easily fits in a USPS medium flat rate box, so $45ish would be the max...maybe less if you use a smaller box or single bottle styro shipper inside another box.
I don't think they make the medium boxes large enough to do it anymore. I think the large flat rate would have to be used. It would be $60.95. Edit - MrKennedy is on to something with the single bottle shipper. If you don't have dimensions 12" or more on any side, you could ship it for $50 or less.
Try it and see, the boxes are free from the USPS (though may not be available at smaller sites). If it doesn't work, use plan B